Light responsive actuating device



INVENTORS HEANEY JOSEPH W ALBIN N. BENSON Nov. 14, 1961 J, w. HEANEY ETAL LIGHT RESPONSIVE ACTUA'IING DEVICE Filed June 5, 1958 WWMp- W QMQ/QM United. States Patent 3,009,103 LIGHT RESPONSIVE ACTUATING DEVICE oseph W. Heaney, Philadelphia, Pa., and Albin N. Benson, Cocoa Beach, Fla., assignors to the United States of America as represented by the Secretary of the Filed June 5, 1958, Ser. No. 740,174 1 Claim. (Cl. 324-68) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to time measuring devices and more particularly to a device for measuring exceedingly short intervals of time such as the duration of the flash incident to the firing of a primer or the like.

Heretofore such measurements have been made by recording the flash on a photographic film moving at a known speed. This method of measurement has the disadvantage that it involves the development of the film and the converting of the photographic record into time. The present invention is distinguished from this photographic record method by the fact that it operates directly in response to a flash to produce a positive and instantaneous measure of the duration of the flash. To this end, there is provided means which function to admit high frequency oscillations to an oscillation counter only during the persistence of the flash.

The invention will be better understood from the following description when considered in connection with the accompanying drawing and its scope is indicated by the appended claim.

The single figure of the drawing is a wiring diagram of the device.

This diagram illustrates a power supply unit 10, a

switching circuit -11, a gate tube 12, a high frequency oscillator 13, a shaper and amplifier 14, and an oscillation counter 15.

The power supply unit 10 is of a well known type. It is adapted to be energized from an alternating current 110 volt source and has three direct current output terminals; a terminal 16 being at ground potential, a terminal 17 being at +300 volts and a terminal 18 being at -300 volts.

The direct current output terminals 16, 17 and 18 are connected to the switching circuit 11 which is controlled by a photocell 63 and includes the two halves 20 and 21 of a 12AU7 duo-triode and a 12AU6 pentode 22.

The +300 volt lead 17 is connected (1) to the anode 23 of the photocell 63 through a resistor 24, (2) to the anode 25 of the triode 20 through a resistor 26, (3) to the anode 27 of the triode 21 through a resistor 28, (4) to the anode 29 of the pentode 22 through a resistor 30, and to the screen grid 31 of the pentode 22 through a resistor 32. The cathodes 3-3, 34 and 35 of the triodes 20 and 21 and the pentode 22 are connected to the ground terminal 16. The cathode 9 of the photocell 63 is connected through a resistor 36 to the adjustable contact of a potentiometer 37.

The potentiometer 37 is connected between the ground terminal 16 and a negative output lead 38 through a resistor 39. A resistor 40 and a switch 41 connected in shunt to the potentiometer 37 are provided for calibration purposes.

"ice

The anode 23 of the photocell 63 is connected to the ground terminal 16 through a resistor 42 and its cathode 9 is connected to the grid 43 of the triode 20 through a resistor '44. The anode 25 of the triode 20 is connected through a resistor 45, a potentiometer 46 and a resistor 47 to the -300 volt output lead 18, the adjustable contact of this potentiometer being connected to the grid 48 of the triode 21. The anode 27 of the triode 21 is connected through a potentiometer 49 to the 300 volt output lead, the adjustable contact of this potentiometer being connected through a resistor 50 to the control 51 of the pentode 22. This pentode has its second grid 31 connected to ground through a resistor 52 and its anode 29 connected through a resistor 53, a potentiometer 54 and a resistor 55 to the 300 volt output lead 18. The movable contact of the potentiometer 54 is connected to the grid 62 of the gate tube 12.

In the standby condition of the switching circuit 11, its various potentiometers are so adjusted and its various resistors are so proportioned that (1) the triode 20 is non-conducting, (2) the triode 21 is conducting, (3) the pentode 22 is non-conducting, and (4) a more positive potential is applied to the grid 62 of the gate tube 12.

When light is applied to the photocell 19, it draws current through the resistor 36 raising the voltage of the grid 43 to a point where the triode draws current through the resistor 26. This reduces the potential of the grid 48 and cuts oif the current of the triode 21 thereby raising the potential of the grid 51 to a point where the pentode 22 begins to draw current through the resistor 30. This puts on the grid 62 of the gate tube 12 a more negative potential which functions to interrupt the current previously flowing through an anode resistor '55.

It should be understood that with the grid 62 at its more positive potential, the current drawn through the resistor 55 maintains the anodes 56 and 57 of the duotriod-e at a voltage sufficiently low to preclude the transmission of oscillations through the triode 565859. When the current of triode 62-5760 is interrupted, however, the voltage of the anode 56 is raised to a point where the output of the oscillator 13 is transmitted through the triode 565859 and a coupling capacitor 61 to a shaper and amplifier 14 from where it is applied to the decades of the counter 15.

As previously indicated this counter registers the exact number of the oscillations generated while the flash is applied to the photocell, and the transmission of these oscillations to the counter is instantly stopped at the termination of the flash. Since the frequency of the oscillations is known and constant there is immediately available a measure of the duration of the flash.

.We claim:

In a device for measuring the duration of a flash of light, the combination of DC. supply means, a photocell, a first triode interconnected with said supply means said photocell to be nonconducting only while no light is applied to said photocell, said first triode having an anode, a second triode interconnected with said D.C. supply means and having a grid, a first potentiometer, said anode of said first triode connected to said grid of said second triode through said first potentiometer, said second triode to be conducting only while said first triode is non-conducting, a second potentiometer, a pentode having an anode interconnected with said supply means, a gate device having a plurality of grids, said anode of said pentode 3 4 being connected to one of said grids of said gate device said oscillation generator to said means including a through said second potentiometer, said pentode concounter in response to said potential.

nected to said second triode to provide a more positive output potential only While said second triode is con- References Clted m the file of this patent ducting, an oscillation generator, means including a 5 UNITED STATES PATENTS counter connected to the oscillation generator through 2,484,299 Labrum Oct. 11, 1949 said gate device, said gate device connected between said 2,831,162 Gross Apr. 15, 1958 oscillation generator and said D.C. supply means, said 2,851,596 Hilton Sept. 9, 1958 gate device being operable to interrupt the output of 2,877,412 Most Mar. 10, 1959 

